How works heart Rate on Sense 2

[Friender]

I don't know if anyone else has noticed this on their Sense 2, but mine every time i take it off will "track" the heart rate from my watch band, it will always hover around 82 - 85 bpm, and before someone says that "it takes 5 minutes for it to registered based on the frequency it measures heart rate" as I have seen in plenty of other posts, mine will do this the entire time it has made contact with the band on its back.
This being Fitbit's high end smartwatch I am concerned how this device is even FDA approved to measure through an ECG with this inaccurate heart rate sensor.

Moderator edit: clarified subject.

[t.parker]

FDA approved ECG sensor only which is not the same that tracks HR 24/7.

[Talahthas]

Welcome to the Fitbit community, @Friender!

To get a deeper insight on how ECG on your Sense 2 is working, I'd suggest having a closer look here:

What is the Fitbit ECG app? 

If you're having heart rate issues and want to use Fitbit's ECG feature in dialog with your doctor, there's a dedicated manual:

Fitbit ECG App Physician’s Guide

[Dopovo]

Honestly if you want an accurate HR sensor it's better to move to another brand.

[LZeeW]

@Friender   Your continuous heart rate measurements come from the optical heart rate monitor (OHRM), the green LEDs.  When you take your Sense off, the LEDs are supposed to turn off.  Sometimes you place it in a position and the LEDs don't turn off.  The emitters are emitting, light gets reflected back, and the sensors sense.  This is completely spurious data, but the algorithms try to make sense of it.  Please make sure the LEDs turn off when you remove your Sense.  Like @t.parker wrote, the ECG uses different sensors, the exposed stainless steel on the back and the two unobtrusive sensors on the frame.